Field of the Invention
The invention relates to an electronic circuit element, a signal generator and a method for generating a signal, and particularly relates to an oscillator, a clock generator and a method for generating a clock signal.
Description of Related Art
An oscillator is an important component in many electronic systems, and may be applied in varies electronic circuit devices. It is very important for an oscillator to output an oscillation signal with accurate and stable frequency. Regarding a current oscillator applied to an electronic circuit, common factors that may affect the oscillation frequency include temperature variation, process variation and electromagnetic interference, etc., and such factors may cause a frequency drift to influence accuracy and stableness of the frequency. According to the conventional technique, a method for resolving the above problem is to adjust a capacitance of a varactor in the oscillator to compensate the drifted oscillation frequency, so as to maintain the accuracy and stableness of the oscillation frequency. However, the varactor is liable to produce a non-ideal second order effect or produce a parasitic capacitance in a high frequency circuit, and such problem may influence an operation of the circuit component and reliability thereof.